Employees dug a trench near a water pump that was previously installed to move water from an above-ground water tank to a future development (the tank was empty as it was still under construction). The employees were to cut into a 20-foot long PVC waterpipe and reroute it to the water pump station. The employees believed that water was inside the pipe when they began to cut. The pipe exploded as soon as the saw breached the piping surface. The pipe had pressurized air inside, resulting in the explosion due to release of pressure. Two employees were hospitalized.